Paper is gaining on plastic as an ingredient in mulches that are used to grow fruits and vegetables.
The United States Department of Agriculture’s Agricultural Research Service says this is mainly because paper mulch coated in vegetable oil may be cheaper than plastic mulches, which are expensive to remove.
Brown paper coated with vegetable oils, such as soybean and linseed oil, can protect the crop from weeds and insects and is biodegradable, said ARS chemist Randal L. Shogren at the National Centre for Agricultural Utilization Research in Peoria, Illinois.
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That gives paper a big advantage over plastic mulches, which cost $240 (US) an acre. Soy oil costs about 15 cents a pound, so growers and home gardeners can expect a reasonable cost for paper mulches made with vegetable oil.
Shogren coated plain brown kraft paper, which is used to make grocery store bags, with several types of vegetable oils, including soybean, linseed and a chemically modified soybean oil, plus a catalyst. The vegetable oil-coated paper withstood wind and rain long enough for the crop to grow, but then began degrading into the soil.
In trials, Shogren found that kraft paper treated with a combination of epoxidized soybean oil and citric acid held up for 13 weeks compared to untreated kraft paper, which was 50 percent degraded in 21/2 weeks.
A U.S. patent on the technology has been approved.
Field trials in Live Oak, Florida, in co-operation with the University of Florida in Gainesville, are in progress. Field trials are also planned with an industry partner.
